Unable to find Kassa Fabrication Shoulders in Citadel Cipritine Armory

I just started playing a new character, i just finished playing Grissom Academy side mission and i am now in citadel trying to purchase the Kassa Fabrication Shoulders in Citadel Cipritine Armory but i was unable to find it.

Do I have to play till a certain stage to unlock it in the store or is it a bug ?